Configuration mapping in an atm-based wide area network

ABSTRACT

A destination local area network (LAN) and a local LAN are coupled by an ATM-based wide area network (WAN). Each LAN includes a router. The WAN includes at least two ATM switches having switch ports. In order to identify and map a connection between the destination LAN and the local LAN, an end-to-end LAN-WAN-LAN connection components template is created. The template contains a number of fields which are populated during the course of identifying the connection. The connection is identified by using IP addresses, subnet masks and virtual circuit identifier values of ATM interfaces on the routers. Virtual circuit identifier values associated with pairs of IP addresses in the connection are identified, and associated with identifier values from the ATM interfaces on the routers. The associated configuration information and components of the WAN are retrieved and stored alongside entries in the list.

RELATED APPLICATIONS

This application is related to the co-pending U.S. application Ser. No.09/528,843 filed Mar. 20, 2000 and entitled “CONFIGURATIONIDENTIFICATION AND MAPPING IN A FRAME RELAY-ATM SERVICEINTERWORKING-BASED WIDE AREA NETWORK” and is assigned to the owner ofthat application.

FIELD OF THE INVENTION

The present invention relates to a configuration mapping method andapparatus in a network having multiple local-area networks (LANs)connected by an ATM-based wide-area network (WAN).

BACKGROUND OF THE INVENTION

The success of the modern business enterprise depends heavily on thecomputing and communications infrastructure that supports it. Thisinfrastructure is considered a strategic asset by businesses, and haschanged dramatically over the years as a result of the evolution in dataprocessing and telecommunications. Because of recent advances incomputing and telecommunications, companies are rapidly adopting newways of doing business, with the end result that mission criticalapplications and operations have moved onto the network and areincreasingly dependent on new networking paradigms.

These new applications generally have some fundamental differences fromearlier data applications. First, they demand much higher bandwidthbecause the amount of traffic generated by them is so much greater.Second, there is a greater need for network connectivity among a muchlarger end-user population. Where, in the past, the network simplyconnected internal, specialized functional areas, the modern networkinterconnects virtually everyone within the corporate structure.Traditional methods of connecting occasional users to the networkinvolve the use of dial-up lines of relatively low speed, which are notsatisfactory for meeting today's connectivity requirements.

Another characteristic of the modern business is that it often comprisesmultiple geographically dispersed locations. In addition, many firmspermit or even encourage telecommuting. Newer network services, such asATM, make these practices possible. In particular, ATM makes it possiblefor such far-flung enterprises to exchange information rapidly andeffectively.

One example of the use of ATM technology is as part of a wide-areanetwork (WAN) that is used to interconnect and seamlessly integratemultiple remote local area networks (LANs) to form an enterpriseintranet. One advantage of this scheme is that the WAN is transparent,and the distributed LANs function as a single LAN from the perspectiveof the end-user. However, there is a significant disadvantage to thisscheme. Because the WAN is transparent, the managers of the LANs cannotdiagnose faults within the WAN. Therefore, a LAN manager cannotdetermine whether a network fault lies within the LAN or within the WAN.Additionally, WAN reported faults cannot be correlated to the associatedLAN components.

SUMMARY OF THE INVENTION

According to an illustrative embodiment of the invention, a destinationlocal area network (LAN) and a local LAN are coupled by an ATM-basedwide area network (WAN). Each of the LANs includes a router, and the WANincludes at least two ATM switches having customer switch ports. One ormore ATM interfaces are configured on each router. The interface on therouter of the local LAN and the interface on the router of thedestination LAN form an interface end-point pair. In order to identify aconnection between the destination LAN and the local LAN, an end-to-endLAN-WAN-LAN connection components template is created. The templatecontains a number of fields, which are populated during the process ofidentifying the end-point to end-point connection.

ATM interfaces are identified on each router. The network addressesconform to Internet Protocol (IP) and are part of the same subnet. TheIP address, IP subnet mask, city, state and the VPI/VCI (“virtualcircuit identifier”) value are retrieved from each of the ATMinterfaces, and those values are stored to create a list describing thephysical and logical characteristics of the ATM interface. A pair ofnetwork addresses is identified using the IP address in conjunction withthe subnet mask stored for each ATM interface in the list. The virtualcircuit identifier values associated with each of the network IPaddresses are identified. WAN configuration data are retrieved andprepared so as to permit LAN-to-WAN correlation. Preparation involvesthe capitalization of all characters in the city and state names in thelist of ATM interfaces, and the manipulation by algorithm of thecharacters forming the city name, which limits its final length andwhich excludes specific character types such as vowels from theresultant string. The city, state and pair of virtual circuit identifiervalues of the ATM interfaces on the LANs are associated with the city,state and pair of virtual circuit identifier values on the WAN. Theassociated configuration information and components of the WAN areretrieved and stored alongside entries in the list of ATM interfaces.

Further features and advantages of the present invention, as well as thestructure and operation of various embodiments of the present inventionare described in detail below with reference to the accompanyingdrawings. In the drawings, like reference numbers indicate identical orfunctionally similar elements. Additionally, the left-most digit(s) of areference number identifies the drawing in which the reference numberfirst is appears.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an ATM-based communications network.

FIGS. 2 and 3 schematically illustrate ATM interfaces of local anddestination LANs in the communication network depicted in FIG. 1.

FIG. 4 is a flow chart depicting the topology discovery process of thepresent invention according to a preferred embodiment

FIG. 5 is a block diagram of an example computer system for implementingthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

The preferred embodiment is discussed in detail below. While specificsteps, configurations and arrangements are discussed, it should beunderstood that this is done for illustrative purposes only. A personskilled in the relevant art will recognize that other steps,configurations and arrangements can be used without departing from thespirit and scope of the present invention.

FIG. 1 depicts an ATM-based communications network 100. Network 100includes two local-area networks (LANs), referred to as local LAN 104and destination LAN 106, which are coupled by a wide-area network (WAN)102. WAN 102 is an ATM network. Local LAN 104 includes a router 116(e.g., a router manufactured by Bay Networks). The router 116 is coupledat ATM interface 117 to port 128 on an ATM switch 108 within WAN 102 viaan access circuit 120 that includes a DSU-to-CSU converter (“DSU/CSU”)112. Destination LAN 106 includes a router 118 (e.g., a switch routermanufactured by Cisco). The router 118 is coupled at ATM interface 119to port 130 on an ATM switch 110 within WAN 102 by an access circuit 122without a DSU/CSU.

A digital service unit (DSU) is a device used in digital transmissionfor connecting a channel service unit (CSU) to data terminal equipment(a terminal or computer), as is also well known in the relevant arts. ADSU provides a standard interface to a user's terminal which iscompatible with modems and handles such functions as signal translation,regeneration, reformatting, and timing. The transmitting portion of theDSU processes the customer's signal into bipolar pulses suitable forextract timing information and to regenerate mark and space informationfrom the received bipolar signal.

A channel service unit (CSU) is a type of interface device used toconnect a terminal or computer to a digital medium, as is well known inthe relevant arts. A CSU is provided by the communication carrier tocustomers who wish to use their own equipment to retime and regeneratethe incoming signals. The customer must supply all of the transmitlogic, receive logic, and timing recovery in order to use the CSU.

A router can have many ATM interfaces. ATM interface 117 on router 116within local LAN 104 is connected by DSU/CSU 112 to the ATM switch 108,which includes a switch port 128. Interface 119 on router 118 withindestination LAN 106 is connected to ATM switch 110. ATM switch 110includes a switch port 130. DSU/CSU 112 is coupled to ATM switch 108 byaccess circuit 120 at switch port 128. Destination LAN 106 is coupled toATM switch 110 at switch port 130 by access circuit 122. ATM interface117 on router 116 of the local LAN 104 and ATM interface 119 on router118 of the destination LAN 106 in the communications network 100depicted in FIG. 1 are schematically illustrated as templates containinginformation in FIGS. 2 and 3, respectively.

A VPI/VCI (“virtual circuit identifier”) value is associated with ATMinterface 117 on the router of the local LAN 104, as shown in FIG. 2. AVPI/VCI value is a logical ID that defines a path of a data packet froman ATM interface on a router to a switch port on an ATM switch. Avirtual circuit identifier value is similarly associated with ATMinterface 119 on the router of the destination LAN 106, as shown in FIG.3.

Within the WAN 102, ATM switch 108 and ATM switch 110 may be connecteddirectly, or indirectly by one or more other ATM switches. For ease ofdiscussion, ATM switches 108 and 110 are shown directly connected by acircuit 140.

In general, each LAN maintains configuration information for itscomponents. This configuration information is generally stored either onthe components themselves, or on a network management system (NMS)within or attached to the LAN. When a fault occurs within a LAN, thatLAN's configuration information is generally used to diagnose andcorrect the fault.

Compound networks such as network 100 are designed so that the WANcomponent is completely transparent to the LANs. The objective is tomake it appear that the local and destination LANs are directlyconnected. One common application of this technique is to create anintranet for a company by connecting multiple LANs that are distant fromone another. In the specific embodiment illustrated in FIG. 1, the ATMinterface 117 on local LAN 104 and the ATM interface 119 on destinationLAN 106 are part of the same intranet or IP subnet.

One disadvantage of the conventional LAN-WAN-LAN arrangement is thatproblems occurring within the WAN cannot be diagnosed by the managers ofthe LANs because configuration information in the WAN is not availableto them. WAN configuration information is generally stored either withinthe WAN components or within network management systems (NMSs) within orattached to the WAN. The present invention addresses this problem bycollecting network component information from both LAN and WAN sourcesand combining this information to produce an end-to-end LAN-WAN-LANtopology of the network.

The WAN connection between access circuit 120 and access circuit 122 isoften referred to as a permanent virtual circuit (PVC). Each PVC withinan ATM network is identified by a pair of ATM customer switch ports andby a pair of VPI/VCI (“virtual circuit identifier”) values. For example,the PVC connecting the local LAN 104 and the destination LAN 106 isidentified by the local ATM customer switch port 128, a local VPI/VCIvalue for the ATM interface 117 on router 116, a destination ATMcustomer switch port 130, and a destination VPI/VCI value for the ATMinterface 119 on router 118. Other configuration information isavailable to completely define the WAN components, the ATM switch 108,and the ATM switch 110.

FIG. 4 is a flow chart depicting the topology discovery process of thepresent invention according to a specific embodiment. In the specificembodiment, this process is executed by topography discovery unit (TDU)150, which is attached to local LAN 104. An example of the structure ofTDU 150 is discussed in detail below.

In step 402, TDU 150 creates a connection components template. Theconnection components template is an array list. That is, each entry onthe list is itself an array. Data that characterize the physical devicesand configuration components needed to map an end-to-end topology for anATM-based LAN-WAN-LAN network are stored in the array. An exemplaryconnection components template is presented in TABLE I. Certain fieldsof the template are needed to aid in network address derivation and inmatching the LAN data to WAN data components configured on ATM switches.

The template presented in TABLE I is the repository of information thatis gathered and identified in the course of the topology discoveryprocess. The template stores the information that is identified in theend-to-end topology from the local side of the WAN through the WAN tothe destination side of the WAN.

TABLE I 1. Local router (hostname) 2. Local router interface IP address3. Local router interface IP Sub Net Mask 4. Local router InterfaceDescription 5. Local router interface protocol 6. Local router city andstate 7. Local router ATM (VPI/VCI) 8. ATM switch local Access Circuit9. ATM switch local (customer) port 10. ATM switch local port city andstate 11. Local ATM (VPI/VCI) 12. Destination ATM (VPI/VCI) 13. ATMswitch destination (customer) port 14. ATM switch destination (customer)port city and state 15. ATM destination Access Circuit 16. Destinationrouter (hostname) 17. Destination router interface description 18.Destination router interface IP address 20. Destination interfaceprotocol 21. Destination router interface IP address 23. Destinationrouter city and state 25. Destination router ATM (VPI/VCI)

In step 404, TDU 150 identifies all the ATM interfaces on the routers inthe intranet. The ATM interfaces at each router are the end points ofthe end-to-end topology of the network. The database of a discoverynetwork management system (NMS), router configurations, or direct accessto MIB (management information base) objects on routers can be used toperform this identification. An example of a network management system(NMS) is Hewlett Packard's Network Node Manager & OpenView products.Because not all routers may be present in the NMS database, routerconfiguration files are used to augment this list. This ensures thatrouters not previously discovered by the NMS are included in thetopology discovery process.

In step 406, TDU 150 examines each of the ATM interfaces and retrievesand stores the IP address, the subnet mask, the city, the state, and theVPI/VCI (“virtual circuit identifier”) for each ATM interface, therebycreating a list of physical and logical information representing the ATMinterface end points.

In step 408, TDU 150 uses the IP address in conjunction with the subnetmask stored for each ATM interface in the list to derive the destinationIP address. TDU 150 identifies in the list the two IP addresses that arepart of the same IP subnet, thereby identifying the end-point interfacepair of network IP addresses. The network address at each ATM interfacebelongs to an IP subnet (i.e., the same intranet). Each entry on thelist is augmented with corresponding values from the associated ATMinterface end-point.

Optionally, TDU 150 uses a separate auxiliary process to derive thedestination IP addresses if they are not found on the list. In step 410,this auxiliary process uses the interface's IP address and subnet maskto locate the destination IP address. This is done by pinging each ofthe potential addresses. A router IP address that responds to the pingis the destination IP address.

Some component manufacturers do not use a standard managementinformation base (MIB) for representing network configuration. Instead,manufacturers such as Bay Networks use a non-standard information base,referred to as a “private MIB.” Because information in private MIBs doesnot conform to a MIB standard, ATM interface information for thesedevices is not accurately represented in the NMS database. For thesedevices, ATM interface information is obtained by accessing the MIBobjects resident on the device. Configuration data for routersmanufactured by Bay Networks can also be obtained from an ASCII dataextract of the configuration or by router commands. In FIGS. 2 and 3,the ATM interfaces are represented schematically as templates containinginformation characterizing the physical and logical aspects of operationof the routers to direct and redirect data packets.

In step 412, TDU 150 identifies the virtual circuit identifier valueassociated with each of the pair of network IP addresses.

In step 414, TDU 150 retrieves and prepares WAN configuration data so asto permit LAN-to-WAN correlation. Specifically, the city and state arereformatted so that their values are stored in a manner that will permitcomparison of a LAN city to a WAN city and a LAN state to a WAN state.The characters forming the state and city names in the list are allcapitalized. The city names are further manipulated by algorithm tocreate a character string which limits the length of the name and whichexcludes certain characteristics from the name such as vowels.

In step 416, TDU 150 associates the city, state and pair of virtualcircuit identifier values of the ATM interfaces on the LANs with thecity, state and pair of virtual circuit identifier values on the WAN.Use of the city and state values are used only when the virtual circuitidentifier values alone are not sufficient to ascertain the correct LANto WAN association.

In step 418, TDU 150 retrieves the associated configuration informationand components on the WAN and stores them alongside entries in the listthat correspond to the ATM interface end-points. That is, the fields ofthe connection components template presented in TABLE I are populated.The resultant TABLE I contains a list of data entries, where the dataentries indicate the physical and logical components of a LAN-WAN-LANcircuit.

TDU 150 of the present invention may be implemented using hardware,software or a combination thereof and may be implemented in a computersystem or other processing system. In an illustrative embodiment, theinvention is directed toward one or more computer systems capable ofcarrying out the functionality described herein. An example computersystem 500 is shown in FIG. 5. The computer system 500 includes one ormore processors, such as processor 504. The processor 504 is connectedto a communication bus 506. Various software embodiments are describedin terms of this example computer system. After reading thisdescription, it will become apparent to a person skilled in the relevantart how to implement the invention using other computer systems and/orcomputer architectures.

Computer system 500 also includes a main memory 508, preferably randomaccess memory (RAM), and can also include a secondary memory 510. Thesecondary memory 510 can include, for example, a hard disk drive 512and/or a removable storage drive 514, representing a floppy disk drive,a magnetic tape drive, an optical disk drive, etc. The removable storagedrive 514 reads from and/or writes to a removable storage unit 518 in awell-known manner. Removable storage unit 518 represents a floppy disk,magnetic tape, optical disk, etc. which is read by and written to byremovable storage drive 514. As will be appreciated, the removablestorage unit 518 includes a computer usable storage medium having storedtherein computer software and/or data.

In alternative embodiments, secondary memory 510 may include othersimilar means for allowing computer programs or other instructions to beloaded into computer system 500. Such means can include, for example, aremovable storage unit 522 and an interface 520. Examples of suchinclude a program cartridge and cartridge interface (such as that foundin video game devices), a removable memory chip (such as an EPROM, orPROM) and associated socket, and other removable storage units 522 andinterfaces 520 which allow software and data to be transferred from theremovable storage units to computer system 500.

Computer system 500 can also include a communications interface 524.Communications interface 524 allows software and data to be transferredbetween computer system 500 and external devices. Examples ofcommunications interface 524 can include a modem, a network interface(such as an Ethernet card), a communications port, a PCMCIA slot andcard, etc. Software and data transferred via communications interface524 are in the form of signals which can be electronic, electromagnetic,optical or other signals capable of being received by communicationsinterface 524. These signals are provided to communications interface524 via a communications path 526. This communications path 526 carriessignals and can be implemented using wire or cable, fiber optics, aphone line, a cellular phone link an RF link and other communicationschannels.

In this document, the terms “computer program medium” and “computerusable medium” are used to generally refer to media such as removablestorage device 518, a hard disk installed in hard disk drive 512, andcommunications path 526. These computer program products are means forproviding software to computer system 500.

Computer programs (also called computer control logic) are stored inmain memory 508 and/or secondary memory 510. Computer programs can alsobe received via communications interface 524. Such computer programs,when executed, enable the computer system 500 to perform the features ofthe present invention as discussed herein. In particular, the computerprograms, when executed, enable the processor 504 to perform thefeatures of the present invention. Accordingly, such computer programsrepresent controllers of the computer system 500.

In an embodiment where the invention is implemented using software, thesoftware may be stored in a computer program product and loaded intocomputer system 500 using removable storage drive 514, hard drive 512 orcommunications interface 524. The control logic (software), whenexecuted by the processor 504, causes the processor 504 to perform thefunctions of the invention as described herein.

In another embodiment, the invention is implemented primarily inhardware using, for example, hardware components such as applicationspecific integrated circuits (ASICs). Implementation of the hardwarestate machine so as to perform the functions described herein will beapparent to persons skilled in the relevant art(s). In yet anotherembodiment, the invention is implemented using a combination of bothhardware and software.

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample, and not limitation. It will be apparent to persons skilled inthe relevant arts that various changes in form and detail can be madewithout departing from the spirit and scope of the present invention.Thus the present invention should not be limited by any of theabove-described exemplary embodiments, but should be defined only inaccordance with the following claims and their equivalents.

1. A method for identifying a connection between a destination localarea network (LAN) and a local LAN where said LANs are coupled by anATM-based wide area network (WAN), wherein each of said LANs includes arouter, and wherein said WAN includes at least two ATM switches, themethod comprising the steps of: identifying one or more ATM interfaceson each router; retrieving and storing an IP address, a subnet mask, acity, a state, and a virtual circuit identifier from each ATM interface,thereby identifying a list of entries; using the IP address inconjunction with the subnet mask stored for each ATM interface in thelist to derive a destination IP address, thereby identifying a pair ofnetwork IP addresses; identifying a virtual circuit identifier valueassociated with each of the pair of network IP addresses; retrieving andpreparing WAN configuration data so as to permit a LAN-to-WANcorrelation; associating the city, state, and pair of virtual circuitidentifier values of the ATM interfaces on the LANs with the city, stateand pair of virtual circuit identifier values on the WAN; and retrievingand storing the associated configuration information and components ofthe WAN along with the entries of the list.
 2. The method of claim 1,wherein identifying one or more ATM interfaces on each router comprisesthe step of: querying LAN management information including at least oneof a network management system database, router command, routerconfiguration files, and router management information base objects. 3.The method of claim 1, wherein retrieving and storing an IP address, asubnet mask, a city, a state, and a virtual circuit identifier valuefrom each ATM interface comprises the step of: querying LAN managementinformation including at least one of a network management systemdatabase, router command, router configuration files, and routermanagement information base objects.
 4. The method of claim 1, furthercomprising the step of: creating a connection components template. 5.The method of claim 1, wherein: said pair of network IP addresses arepart of the same subnet.
 6. The method of claim 5, wherein using the IPaddress in conjunction with the subnet mask stored for each ATMinterface in the list to derive a destination IP address comprises thestep of: matching pairs of IP addresses using their subnet addresses. 7.A computer program product for identifying a connection between adestination local area network (LAN) and a local LAN where said LANs arecoupled by an ATM-based wide area network (WAN), wherein each of saidLANs includes a router, and wherein said WAN includes at least two ATMswitches, said computer program product comprising: a computer usablemedium having computer readable program code means embodied in saidmedium, said computer readable program code means comprising: a computerreadable first program code means for causing a computer to identify oneor more ATM interfaces on each router; a computer readable secondprogram code means for causing a computer to retrieve and store an IPaddress, a subnet mask, a city, a state, and a virtual circuitidentifier from each ATM interface, thereby identifying a list ofentries; a computer readable third program code means for causing acomputer to use the IP address in conjunction with the subnet maskstored for each ATM interface in the list to derive a destination IPaddress, thereby identifying a pair of network IP addresses; a computerreadable fourth program code means for causing a computer to identifythe virtual circuit identifier value associated with each of the pair ofnetwork IP addresses; a computer readable fifth program code means forcausing a computer to retrieve and prepare WAN configuration data so asto permit a LAN-to-WAN correlation; a computer readable sixth programcode means for causing a computer to associate the city, state, and pairof virtual circuit identifier values of the ATM interface points on theLANs with the city, state and pair of virtual circuit identifier valueson the WAN; and a computer readable seventh program code means forcausing a computer to retrieve and store the associated configurationinformation and components of the WAN along with the entries of thelist.
 8. The computer program product of claim 7, wherein said computerreadable first program code means comprises: a computer readable programcode means for causing a computer to query LAN management informationincluding at least one of a network management system database, routercommand, router configuration files, and router management informationbase objects.
 9. The computer program product of claim 7, wherein saidcomputer readable second program code means comprises: a computerreadable program code means for causing a computer to query LANmanagement information including at least one of a network managementsystem database, router command, router configuration files, and routermanagement information base objects.
 10. The computer program product ofclaim 7, wherein said computer readable program code means furthercomprises: a computer readable eighth program code means for causing acomputer to create a connection components template.
 11. The computerprogram product of claim 7, wherein: said pair of network IP addressesare part of the same subnet.
 12. The computer program product of claim11, wherein said computer readable third program code means comprises: acomputer readable program code means for causing a computer to matchpairs of IP addresses using their subnet addresses.
 13. An apparatus formapping a connection between a destination local area network (LAN) anda local LAN where said LANs are coupled by an ATM-based wide areanetwork (WAN), wherein each of said LANs includes a router, and whereinsaid WAN includes at least two ATM switches, the apparatus comprising:means for identifying one or more ATM interfaces on each router; meansfor retrieving and storing an IP address, a subnet mask, a city, astate, and a virtual circuit identifier from each ATM interface, therebyidentifying a list of entries; means for using the IP address inconjunction with the subnet mask stored for each ATM interface in thelist to derive a destination IP address, thereby identifying a pair ofnetwork IP addresses; means for identifying a virtual circuit identifiervalue associated with each of the pair of network IP addresses; meansfor retrieving and preparing WAN configuration data so as to permit aLAN-to-WAN correlation; means for associating the city, state, and pairof virtual circuit identifier values of the ATM interfaces on the LANswith the city, state and pair of virtual circuit identifier values onthe WAN; and means for retrieving and storing the associatedconfiguration information and components of the WAN along with theentries of the list.
 14. The apparatus of claim 13, wherein said meansfor identifying one or more ATM interfaces on each router comprises:means for querying LAN management information including at least one ofa network management system database, router command, routerconfiguration files, and router management information base objects. 15.The apparatus of claim 13, wherein said means for retrieving and storingan IP address, a subnet mask, a city, a state, and a virtual circuitidentifier value from each ATM interface comprises: means for queryingLAN management information including at least one of a networkmanagement system database, router command, router configuration files,and router management information base objects.
 16. The apparatus ofclaim 13, further comprising: means for creating a connection componentstemplate.
 17. The apparatus of claim 13, wherein: said pair of networkIP addresses are part of the same subnet.
 18. The apparatus of claim 17,wherein said means for using the IP address in conjunction with thesubnet mask stored for each ATM interface in the list to derive adestination IP address comprises: means for matching pairs of IPaddresses using their subnet addresses.